Develop Reference

is there a way to continue running intervals in javascript even after changing tabs or minimizing the window? [duplicate]

I have a setInterval running a piece of code 30 times a second. This works great, however when I select another tab (so that the tab with my code becomes inactive), the setInterval is set to an idle state for some reason.
I made this simplified test case (http://jsfiddle.net/7f6DX/3/):
var $div = $('div');
var a = 0;
setInterval(function() {
a++;
$div.css("left", a)
}, 1000 / 30);
If you run this code and then switch to another tab, wait a few seconds and go back, the animation continues at the point it was when you switched to the other tab.
So the animation isn't running 30 times a second in case the tab is inactive. This can be confirmed by counting the amount of times the setInterval function is called each second - this will not be 30 but just 1 or 2 if the tab is inactive.
I guess that this is done by design so as to improve system performance, but is there any way to disable this behavior?
It’s actually a disadvantage in my scenario.

On most browsers inactive tabs have low priority execution and this can affect JavaScript timers.
If the values of your transition were calculated using real time elapsed between frames instead fixed increments on each interval, you not only workaround this issue but also can achieve a smother animation by using requestAnimationFrame as it can get up to 60fps if the processor isn't very busy.
Here's a vanilla JavaScript example of an animated property transition using requestAnimationFrame:
var target = document.querySelector('div#target')
var startedAt, duration = 3000
var domain = [-100, window.innerWidth]
var range = domain[1] - domain[0]
function start() {
startedAt = Date.now()
updateTarget(0)
requestAnimationFrame(update)
}
function update() {
let elapsedTime = Date.now() - startedAt
// playback is a value between 0 and 1
// being 0 the start of the animation and 1 its end
let playback = elapsedTime / duration
updateTarget(playback)
if (playback > 0 && playback < 1) {
// Queue the next frame
requestAnimationFrame(update)
} else {
// Wait for a while and restart the animation
setTimeout(start, duration/10)
}
}
function updateTarget(playback) {
// Uncomment the line below to reverse the animation
// playback = 1 - playback
// Update the target properties based on the playback position
let position = domain[0] + (playback * range)
target.style.left = position + 'px'
target.style.top = position + 'px'
target.style.transform = 'scale(' + playback * 3 + ')'
}
start()
body {
overflow: hidden;
}
div {
position: absolute;
white-space: nowrap;
}
<div id="target">...HERE WE GO</div>
For Background Tasks (non-UI related)
#UpTheCreek comment:
Fine for presentation issues, but still
there are some things that you need to keep running.
If you have background tasks that needs to be precisely executed at given intervals, you can use HTML5 Web Workers. Take a look at Möhre's answer below for more details...
CSS vs JS "animations"
This problem and many others could be avoided by using CSS transitions/animations instead of JavaScript based animations which adds a considerable overhead. I'd recommend this jQuery plugin that let's you take benefit from CSS transitions just like the animate() methods.

I ran into the same problem with audio fading and HTML5 player. It got stuck when tab became inactive.
So I found out a WebWorker is allowed to use intervals/timeouts without limitation. I use it to post "ticks" to the main javascript.
WebWorkers Code:
var fading = false;
var interval;
self.addEventListener('message', function(e){
switch (e.data) {
case 'start':
if (!fading){
fading = true;
interval = setInterval(function(){
self.postMessage('tick');
}, 50);
}
break;
case 'stop':
clearInterval(interval);
fading = false;
break;
};
}, false);
Main Javascript:
var player = new Audio();
player.fader = new Worker('js/fader.js');
player.faderPosition = 0.0;
player.faderTargetVolume = 1.0;
player.faderCallback = function(){};
player.fadeTo = function(volume, func){
console.log('fadeTo called');
if (func) this.faderCallback = func;
this.faderTargetVolume = volume;
this.fader.postMessage('start');
}
player.fader.addEventListener('message', function(e){
console.log('fader tick');
if (player.faderTargetVolume > player.volume){
player.faderPosition -= 0.02;
} else {
player.faderPosition += 0.02;
}
var newVolume = Math.pow(player.faderPosition - 1, 2);
if (newVolume > 0.999){
player.volume = newVolume = 1.0;
player.fader.postMessage('stop');
player.faderCallback();
} else if (newVolume < 0.001) {
player.volume = newVolume = 0.0;
player.fader.postMessage('stop');
player.faderCallback();
} else {
player.volume = newVolume;
}
});

There is a solution to use Web Workers (as mentioned before), because they run in separate process and are not slowed down
I've written a tiny script that can be used without changes to your code - it simply overrides functions setTimeout, clearTimeout, setInterval, clearInterval.
Just include it before all your code.
more info here

Both setInterval and requestAnimationFrame don't work when tab is inactive or work but not at the right periods. A solution is to use another source for time events. For example web sockets or web workers are two event sources that work fine while tab is inactive. So no need to move all of your code to a web worker, just use worker as a time event source:
// worker.js
setInterval(function() {
postMessage('');
}, 1000 / 50);
.
var worker = new Worker('worker.js');
var t1 = 0;
worker.onmessage = function() {
var t2 = new Date().getTime();
console.log('fps =', 1000 / (t2 - t1) | 0);
t1 = t2;
}
jsfiddle link of this sample.

Just do this:
var $div = $('div');
var a = 0;
setInterval(function() {
a++;
$div.stop(true,true).css("left", a);
}, 1000 / 30);
Inactive browser tabs buffer some of the setInterval or setTimeout functions.
stop(true,true) will stop all buffered events and execute immediatly only the last animation.
The window.setTimeout() method now clamps to send no more than one timeout per second in inactive tabs. In addition, it now clamps nested timeouts to the smallest value allowed by the HTML5 specification: 4 ms (instead of the 10 ms it used to clamp to).

For me it's not important to play audio in the background like for others here, my problem was that I had some animations and they acted like crazy when you were in other tabs and coming back to them. My solution was putting these animations inside if that is preventing inactive tab:
if (!document.hidden){ //your animation code here }
thanks to that my animation was running only if tab was active.
I hope this will help someone with my case.

I think that a best understanding about this problem is in this example: http://jsfiddle.net/TAHDb/
I am doing a simple thing here:
Have a interval of 1 sec and each time hide the first span and move it to last, and show the 2nd span.
If you stay on page it works as it is supposed.
But if you hide the tab for some seconds, when you get back you will see a weired thing.
Its like all events that didn't ucur during the time you were inactive now will ocur all in 1 time. so for some few seconds you will get like X events. they are so quick that its possible to see all 6 spans at once.
So it seams chrome only delays the events, so when you get back all events will occur but all at once...
A pratical application were this ocur iss for a simple slideshow. Imagine the numbers being Images, and if user stay with tab hidden when he came back he will see all imgs floating, Totally mesed.
To fix this use the stop(true,true) like pimvdb told.
THis will clear the event queue.

Heavily influenced by Ruslan Tushov's library, I've created my own small library. Just add the script in the <head> and it will patch setInterval and setTimeout with ones that use WebWorker.

Playing an audio file ensures full background Javascript performance for the time being
For me, it was the simplest and least intrusive solution - apart from playing a faint / almost-empty sound, there are no other potential side effects
You can find the details here: https://stackoverflow.com/a/51191818/914546
(From other answers, I see that some people use different properties of the Audio tag, I do wonder whether it's possible to use the Audio tag for full performance, without actually playing something)

I bring here a simple solution for anyone who is trying to get around this problem in a timer function, where as #kbtzr mentioned in another answer we can use the Date object instead of fixed increments to calculate the time that has passed since the beginning, which will work even if you are out from the application's tab.
This is the example HTML.
<body>
<p id="time"></p>
</body>
Then this JavaScript:
let display = document.querySelector('#time')
let interval
let time
function startTimer() {
let initialTime = new Date().getTime()
interval = setInterval(() => {
let now = new Date().getTime()
time = (now - initialTime) + 10
display.innerText = `${Math.floor((time / (60 * 1000)) % 60)}:${Math.floor((time / 1000) % 60)}:${Math.floor((time / 10) % 100)}`
}, 10)
}
startTimer()
That way, even if the interval value is increased for performance reasons of inactive tabs, the calculation made will guarantee the correct time. This is a vanilla code, but I used this logic in my React application, and you can modify it for wherever you need as well.

It is quite old question but I encountered the same issue.
If you run your web on chrome, you could read through this post Background Tabs in Chrome 57.
Basically the interval timer could run if it haven't run out of the timer budget.
The consumption of budget is based on CPU time usage of the task inside timer.
Based on my scenario, I draw video to canvas and transport to WebRTC.
The webrtc video connection would keep updating even the tab is inactive.
However you have to use setInterval instead of requestAnimationFrame but itt is not recommended for UI rendering though.
It would be better to listen visibilityChange event and change render mechenism accordingly.
Besides, you could try what Kaan Soral suggests and it should works based on the documentation.

I modified Lacerda's response, by adding a functioning UI.
I added start/resume/pause/stop actions.
const
timer = document.querySelector('.timer'),
timerDisplay = timer.querySelector('.timer-display'),
toggleAction = timer.querySelector('[data-action="toggle"]'),
stopAction = timer.querySelector('[data-action="stop"]'),
tickRate = 10;
let intervalId, initialTime, pauseTime = 0;
const now = () => new Date().getTime();
const formatTime = (hours, minutes, seconds) =>
[hours, minutes, seconds]
.map(v => `${isNaN(v) ? 0 : v}`.padStart(2, '0'))
.join(':');
const update = () => {
let
time = (now() - initialTime) + 10,
hours = Math.floor((time / (60000)) % 60),
minutes = Math.floor((time / 1000) % 60),
seconds = Math.floor((time / 10) % 100);
timerDisplay.textContent = formatTime(hours, minutes, seconds);
};
const
startTimer = () => {
initialTime = now();
intervalId = setInterval(update, tickRate);
},
resumeTimer = () => {
initialTime = now() - (pauseTime - initialTime);
intervalId = setInterval(update, tickRate);
},
pauseTimer = () => {
clearInterval(intervalId);
intervalId = null;
pauseTime = now();
},
stopTimer = () => {
clearInterval(intervalId);
intervalId = null;
initialTime = undefined;
pauseTime = 0;
},
restartTimer = () => {
stopTimer();
startTimer();
};
const setButtonState = (button, state, text) => {
button.dataset.state = state;
button.textContent = text;
};
const
handleToggle = (e) => {
switch (e.target.dataset.state) {
case 'pause':
setButtonState(e.target, 'resume', 'Resume');
pauseTimer();
break;
case 'resume':
setButtonState(e.target, 'pause', 'Pause');
resumeTimer();
break;
default:
setButtonState(e.target, 'pause', 'Pause');
restartTimer();
}
},
handleStop = (e) => {
stopTimer();
update();
setButtonState(toggleAction, 'initial', 'Start');
};
toggleAction.addEventListener('click', handleToggle);
stopAction.addEventListener('click', handleStop);
update();
html, body {
width: 100%;
height: 100%;
margin: 0;
padding: 0;
}
body {
display: flex;
justify-content: center;
align-items: center;
background: #000;
}
.timer {
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
gap: 0.5em;
}
.timer .timer-display {
font-family: monospace;
font-size: 3em;
background: #111;
color: #8F8;
border: thin solid #222;
padding: 0.25em;
}
.timer .timer-actions {
display: flex;
justify-content: center;
gap: 0.5em;
}
.timer .timer-actions button[data-action] {
font-family: monospace;
width: 6em;
border: thin solid #444;
background: #222;
color: #EEE;
padding: 0.5em;
cursor: pointer;
text-transform: uppercase;
}
.timer .timer-actions button[data-action]:hover {
background: #444;
border: thin solid #666;
color: #FFF;
}
<div class="timer">
<div class="timer-display"></div>
<div class="timer-actions">
<button data-action="toggle" data-state="initial">Start</button>
<button data-action="stop">Stop</button>
</div>
</div>

Note: This solution is not suitable if you like your interval works on the background, for example, playing audio or something else. But if you are confused for example about your animation not working properly when coming back to your page or tab, this is a good solution.
There are many ways to achieve this goal, maybe the "WebWorkers" is the most standard one but certainly, it's not the easiest and handy one, especially If you don't have enough Time, so you can try this way:
The basic concept:
build a name for your interval(or animation) and set your interval(animation), so it would run when user first time open your page : var interval_id = setInterval(your_func, 3000);
by $(window).focus(function() {}); and $(window).blur(function() {}); you can clearInterval(interval_id) everytime browser(tab) is deactived and ReRun your interval(animation) everytime browser(tab) would acive again by interval_id = setInterval();
Sample code:
var interval_id = setInterval(your_func, 3000);
$(window).focus(function() {
interval_id = setInterval(your_func, 3000);
});
$(window).blur(function() {
clearInterval(interval_id);
interval_id = 0;
});

Here's my rough solution
(function(){
var index = 1;
var intervals = {},
timeouts = {};
function postMessageHandler(e) {
window.postMessage('', "*");
var now = new Date().getTime();
sysFunc._each.call(timeouts, function(ind, obj) {
var targetTime = obj[1];
if (now >= targetTime) {
obj[0]();
delete timeouts[ind];
}
});
sysFunc._each.call(intervals, function(ind, obj) {
var startTime = obj[1];
var func = obj[0];
var ms = obj[2];
if (now >= startTime + ms) {
func();
obj[1] = new Date().getTime();
}
});
}
window.addEventListener("message", postMessageHandler, true);
window.postMessage('', "*");
function _setTimeout(func, ms) {
timeouts[index] = [func, new Date().getTime() + ms];
return index++;
}
function _setInterval(func, ms) {
intervals[index] = [func, new Date().getTime(), ms];
return index++;
}
function _clearInterval(ind) {
if (intervals[ind]) {
delete intervals[ind]
}
}
function _clearTimeout(ind) {
if (timeouts[ind]) {
delete timeouts[ind]
}
}
var intervalIndex = _setInterval(function() {
console.log('every 100ms');
}, 100);
_setTimeout(function() {
console.log('run after 200ms');
}, 200);
_setTimeout(function() {
console.log('closing the one that\'s 100ms');
_clearInterval(intervalIndex)
}, 2000);
window._setTimeout = _setTimeout;
window._setInterval = _setInterval;
window._clearTimeout = _clearTimeout;
window._clearInterval = _clearInterval;
})();

I was able to call my callback function at minimum of 250ms using audio tag and handling its ontimeupdate event. Its called 3-4 times in a second. Its better than one second lagging setTimeout

There is a workaround for this problem, although actually the tab must be made active in some window.
Make your inactive tab a separate browser window.
Don't make any other window maximized (unless the maximized window is behind yours).
This should give the browser the impression of always being active.
This is bit cumbersome, but also a quick win. Provided one has control over windows arrangement.

if/else and setInterval

<script>
//when user clicks start button this function ensures all fields //are set to 0 and it
//sets the timer for the game (90seconds) and the second timer to //call showWord() every four seconds to display a new word
function startGame() {
numBadWordsField.innerHTML = '';
numGoodWordsField.innerHTML = '';
numWordsRight = 0;
numWordsWrong = 0;
correctWords = [];
showWord();
gameTimer = setInterval(gameTime, 1000);
timedWordDisplay = setInterval(showWord, 4000);
}
//this function is set to repeat every four seconds unless the user //types the word
//correctly in which case code in the checkWord() function resets setInterval then and a new word appears
function showWord() {
let randomNum = Math.floor(Math.random()*wordsLevelOne.length);
currentWord = wordsLevelOne[randomNum];
//i put all correctly typed words in an array to avoid them being repeated
//if the random word has been typed correctly and is in the array then i tell the
//program to repeat the function until a new word is found.
if (correctWords.includes(currentWord)) {
showWord();
} else {
wordDisplayBox.innerHTML = currentWord;
setInterval(changeBar, 500);
answerBox.focus();
}
}
//this function is called oninput as user types in the word. it works perfectly (i think it does anyways)
//however i cannot figure out how to give instructions in the event the user does not type the
//word correctly before the four seconds are up and the setInterval repeats. I would like to
//in that case increment the words wrong score and reset the fields to be ready for the next
//word to be displayed
function checkWord() {
let currentWordLen = answerBox.value.length;
if (wordDisplayBox.innerHTML === answerBox.value) {
clearInterval(timedWordDisplay);
numWordsRight++;
correctWords.push(currentWord);
numGoodWordsField.innerHTML = numWordsRight;
answerBox.value = '';
answerBox.focus();
wordDisplayBox.innerHTML = '';
showWord();
timedWordDisplay = setInterval(showWord, 4000);
} else if (answerBox.value === currentWord.substring(0, currentWordLen)) {
answerBox.style.borderColor = 'green';
} else {
answerBox.style.borderColor = 'red';
}
}
//different topic than above but i also researched how to make my progress bar fill slowly over the course
//of the four seconds. i have written the following function identically to that on
//w3schools and other code yet it does not work.
//Any ideas?
function changeBar() {
let proBar = document.querySelector('#progressBar');
var width = 1;
var id = setInterval(frame, 10);
function frame() {
if (width >= 100) {
clearInterval(id);
} else {
width++;
proBar.style.width = width + '%';
}
}
}
</script>
This project Im working on is a beginner level speed typing game that displays a different word for the user to type in less than four seconds.I have a setInterval that displays a different word every four seconds unless the user types the word correctly at which point the timer starts over then. What I am stumped at is how can I make it so that if the correct answer is not typed in before the interval resets (at the end of four seconds) the program knows to increment the 'wrong answer' score and to reset the input boxes for the next word just like when it is typed correctly. i have attached the parts of my code i think may be relevant. If anyone has any suggestions let me know. I am eager to learn. **I am not familiar yet with JQuery. Please describe any suggestions using vanilla JS

This feature should be implemented in the showWord function.
showWord is executed after 4 seconds have passed, which is when the time is up. Executing this function means the user has failed to type the word in time.
I would do something like this :
function showWord() {
// At this point, the user has lost. We perform the according operations
numWordsWrong++;
answerBox.value = '';
// etc.
// What follows is the rest of the function you've already implemented
let randomNum = Math.floor(Math.random()*wordsLevelOne.length);
// etc.
}

To answer your question about the progress bar, you are setting an interval to run changeBar every 500 milliseconds, which would cause the progress bar to reset every half second. If you want a delay before starting the progress bar use setTimeout.
In addition, you are running your progress bar to move 1% every 10 milliseconds which would result in the bar completing in 1 second. If you want the bar to complete in 4 seconds, set the id interval to run every 40 milliseconds.
Without seeing your css and html, I have to assume you're using the correct id names in your code but if nothing is happening at all, that could also be the cause.
I have looked at the W3Shools code you reference and I tried to replicate what you were trying to do and got this to work:
<html>
<head>
<style>
#myProgress {
width: 100%;
background-color: #ddd;
}
#myBar {
width: 1%;
height: 30px;
background-color: #4CAF50;
}
</style>
</head>
<body>
<div id="myProgress">
<div id="myBar"></div>
</div>
</body>
<script>
function changeBar() {
let proBar = document.querySelector('#myBar');
var width = 1;
var id = setInterval(frame, 40);
function frame() {
if (width >= 100) {
clearInterval(id);
} else {
width++;
proBar.style.width = width + '%';
}
}
}
setTimeout(changeBar, 100);
</script>
</html>

One solution can be to create a new function (ex : showWordBecauseTimeout) and call it in your setInterval instead of showWord. And call that function in showWord fct instead of in startGame fct.
So the new code would be something like :
function showWord() {
clearInterval(timedWordDisplay);
timedWordDisplay = setInterval(showWordBecauseTimeout, 4000);
// you also need to move the cleaning of the input in the showWord fct
// ...
}
function showWordBecauseTimeout() {
numWordsWrong++;
showWord()
}
Hope that it helps you :).

Why are my setInterval and setTimeout Animations behaving unexpectedly when switching windows [duplicate]

I have a setInterval running a piece of code 30 times a second. This works great, however when I select another tab (so that the tab with my code becomes inactive), the setInterval is set to an idle state for some reason.
I made this simplified test case (http://jsfiddle.net/7f6DX/3/):
var $div = $('div');
var a = 0;
setInterval(function() {
a++;
$div.css("left", a)
}, 1000 / 30);
If you run this code and then switch to another tab, wait a few seconds and go back, the animation continues at the point it was when you switched to the other tab.
So the animation isn't running 30 times a second in case the tab is inactive. This can be confirmed by counting the amount of times the setInterval function is called each second - this will not be 30 but just 1 or 2 if the tab is inactive.
I guess that this is done by design so as to improve system performance, but is there any way to disable this behavior?
It’s actually a disadvantage in my scenario.

On most browsers inactive tabs have low priority execution and this can affect JavaScript timers.
If the values of your transition were calculated using real time elapsed between frames instead fixed increments on each interval, you not only workaround this issue but also can achieve a smother animation by using requestAnimationFrame as it can get up to 60fps if the processor isn't very busy.
Here's a vanilla JavaScript example of an animated property transition using requestAnimationFrame:
var target = document.querySelector('div#target')
var startedAt, duration = 3000
var domain = [-100, window.innerWidth]
var range = domain[1] - domain[0]
function start() {
startedAt = Date.now()
updateTarget(0)
requestAnimationFrame(update)
}
function update() {
let elapsedTime = Date.now() - startedAt
// playback is a value between 0 and 1
// being 0 the start of the animation and 1 its end
let playback = elapsedTime / duration
updateTarget(playback)
if (playback > 0 && playback < 1) {
// Queue the next frame
requestAnimationFrame(update)
} else {
// Wait for a while and restart the animation
setTimeout(start, duration/10)
}
}
function updateTarget(playback) {
// Uncomment the line below to reverse the animation
// playback = 1 - playback
// Update the target properties based on the playback position
let position = domain[0] + (playback * range)
target.style.left = position + 'px'
target.style.top = position + 'px'
target.style.transform = 'scale(' + playback * 3 + ')'
}
start()
body {
overflow: hidden;
}
div {
position: absolute;
white-space: nowrap;
}
<div id="target">...HERE WE GO</div>
For Background Tasks (non-UI related)
#UpTheCreek comment:
Fine for presentation issues, but still
there are some things that you need to keep running.
If you have background tasks that needs to be precisely executed at given intervals, you can use HTML5 Web Workers. Take a look at Möhre's answer below for more details...
CSS vs JS "animations"
This problem and many others could be avoided by using CSS transitions/animations instead of JavaScript based animations which adds a considerable overhead. I'd recommend this jQuery plugin that let's you take benefit from CSS transitions just like the animate() methods.

I ran into the same problem with audio fading and HTML5 player. It got stuck when tab became inactive.
So I found out a WebWorker is allowed to use intervals/timeouts without limitation. I use it to post "ticks" to the main javascript.
WebWorkers Code:
var fading = false;
var interval;
self.addEventListener('message', function(e){
switch (e.data) {
case 'start':
if (!fading){
fading = true;
interval = setInterval(function(){
self.postMessage('tick');
}, 50);
}
break;
case 'stop':
clearInterval(interval);
fading = false;
break;
};
}, false);
Main Javascript:
var player = new Audio();
player.fader = new Worker('js/fader.js');
player.faderPosition = 0.0;
player.faderTargetVolume = 1.0;
player.faderCallback = function(){};
player.fadeTo = function(volume, func){
console.log('fadeTo called');
if (func) this.faderCallback = func;
this.faderTargetVolume = volume;
this.fader.postMessage('start');
}
player.fader.addEventListener('message', function(e){
console.log('fader tick');
if (player.faderTargetVolume > player.volume){
player.faderPosition -= 0.02;
} else {
player.faderPosition += 0.02;
}
var newVolume = Math.pow(player.faderPosition - 1, 2);
if (newVolume > 0.999){
player.volume = newVolume = 1.0;
player.fader.postMessage('stop');
player.faderCallback();
} else if (newVolume < 0.001) {
player.volume = newVolume = 0.0;
player.fader.postMessage('stop');
player.faderCallback();
} else {
player.volume = newVolume;
}
});

There is a solution to use Web Workers (as mentioned before), because they run in separate process and are not slowed down
I've written a tiny script that can be used without changes to your code - it simply overrides functions setTimeout, clearTimeout, setInterval, clearInterval.
Just include it before all your code.
more info here

Both setInterval and requestAnimationFrame don't work when tab is inactive or work but not at the right periods. A solution is to use another source for time events. For example web sockets or web workers are two event sources that work fine while tab is inactive. So no need to move all of your code to a web worker, just use worker as a time event source:
// worker.js
setInterval(function() {
postMessage('');
}, 1000 / 50);
.
var worker = new Worker('worker.js');
var t1 = 0;
worker.onmessage = function() {
var t2 = new Date().getTime();
console.log('fps =', 1000 / (t2 - t1) | 0);
t1 = t2;
}
jsfiddle link of this sample.

Just do this:
var $div = $('div');
var a = 0;
setInterval(function() {
a++;
$div.stop(true,true).css("left", a);
}, 1000 / 30);
Inactive browser tabs buffer some of the setInterval or setTimeout functions.
stop(true,true) will stop all buffered events and execute immediatly only the last animation.
The window.setTimeout() method now clamps to send no more than one timeout per second in inactive tabs. In addition, it now clamps nested timeouts to the smallest value allowed by the HTML5 specification: 4 ms (instead of the 10 ms it used to clamp to).

For me it's not important to play audio in the background like for others here, my problem was that I had some animations and they acted like crazy when you were in other tabs and coming back to them. My solution was putting these animations inside if that is preventing inactive tab:
if (!document.hidden){ //your animation code here }
thanks to that my animation was running only if tab was active.
I hope this will help someone with my case.

I think that a best understanding about this problem is in this example: http://jsfiddle.net/TAHDb/
I am doing a simple thing here:
Have a interval of 1 sec and each time hide the first span and move it to last, and show the 2nd span.
If you stay on page it works as it is supposed.
But if you hide the tab for some seconds, when you get back you will see a weired thing.
Its like all events that didn't ucur during the time you were inactive now will ocur all in 1 time. so for some few seconds you will get like X events. they are so quick that its possible to see all 6 spans at once.
So it seams chrome only delays the events, so when you get back all events will occur but all at once...
A pratical application were this ocur iss for a simple slideshow. Imagine the numbers being Images, and if user stay with tab hidden when he came back he will see all imgs floating, Totally mesed.
To fix this use the stop(true,true) like pimvdb told.
THis will clear the event queue.

Heavily influenced by Ruslan Tushov's library, I've created my own small library. Just add the script in the <head> and it will patch setInterval and setTimeout with ones that use WebWorker.

Playing an audio file ensures full background Javascript performance for the time being
For me, it was the simplest and least intrusive solution - apart from playing a faint / almost-empty sound, there are no other potential side effects
You can find the details here: https://stackoverflow.com/a/51191818/914546
(From other answers, I see that some people use different properties of the Audio tag, I do wonder whether it's possible to use the Audio tag for full performance, without actually playing something)

I bring here a simple solution for anyone who is trying to get around this problem in a timer function, where as #kbtzr mentioned in another answer we can use the Date object instead of fixed increments to calculate the time that has passed since the beginning, which will work even if you are out from the application's tab.
This is the example HTML.
<body>
<p id="time"></p>
</body>
Then this JavaScript:
let display = document.querySelector('#time')
let interval
let time
function startTimer() {
let initialTime = new Date().getTime()
interval = setInterval(() => {
let now = new Date().getTime()
time = (now - initialTime) + 10
display.innerText = `${Math.floor((time / (60 * 1000)) % 60)}:${Math.floor((time / 1000) % 60)}:${Math.floor((time / 10) % 100)}`
}, 10)
}
startTimer()
That way, even if the interval value is increased for performance reasons of inactive tabs, the calculation made will guarantee the correct time. This is a vanilla code, but I used this logic in my React application, and you can modify it for wherever you need as well.

It is quite old question but I encountered the same issue.
If you run your web on chrome, you could read through this post Background Tabs in Chrome 57.
Basically the interval timer could run if it haven't run out of the timer budget.
The consumption of budget is based on CPU time usage of the task inside timer.
Based on my scenario, I draw video to canvas and transport to WebRTC.
The webrtc video connection would keep updating even the tab is inactive.
However you have to use setInterval instead of requestAnimationFrame but itt is not recommended for UI rendering though.
It would be better to listen visibilityChange event and change render mechenism accordingly.
Besides, you could try what Kaan Soral suggests and it should works based on the documentation.

I modified Lacerda's response, by adding a functioning UI.
I added start/resume/pause/stop actions.
const
timer = document.querySelector('.timer'),
timerDisplay = timer.querySelector('.timer-display'),
toggleAction = timer.querySelector('[data-action="toggle"]'),
stopAction = timer.querySelector('[data-action="stop"]'),
tickRate = 10;
let intervalId, initialTime, pauseTime = 0;
const now = () => new Date().getTime();
const formatTime = (hours, minutes, seconds) =>
[hours, minutes, seconds]
.map(v => `${isNaN(v) ? 0 : v}`.padStart(2, '0'))
.join(':');
const update = () => {
let
time = (now() - initialTime) + 10,
hours = Math.floor((time / (60000)) % 60),
minutes = Math.floor((time / 1000) % 60),
seconds = Math.floor((time / 10) % 100);
timerDisplay.textContent = formatTime(hours, minutes, seconds);
};
const
startTimer = () => {
initialTime = now();
intervalId = setInterval(update, tickRate);
},
resumeTimer = () => {
initialTime = now() - (pauseTime - initialTime);
intervalId = setInterval(update, tickRate);
},
pauseTimer = () => {
clearInterval(intervalId);
intervalId = null;
pauseTime = now();
},
stopTimer = () => {
clearInterval(intervalId);
intervalId = null;
initialTime = undefined;
pauseTime = 0;
},
restartTimer = () => {
stopTimer();
startTimer();
};
const setButtonState = (button, state, text) => {
button.dataset.state = state;
button.textContent = text;
};
const
handleToggle = (e) => {
switch (e.target.dataset.state) {
case 'pause':
setButtonState(e.target, 'resume', 'Resume');
pauseTimer();
break;
case 'resume':
setButtonState(e.target, 'pause', 'Pause');
resumeTimer();
break;
default:
setButtonState(e.target, 'pause', 'Pause');
restartTimer();
}
},
handleStop = (e) => {
stopTimer();
update();
setButtonState(toggleAction, 'initial', 'Start');
};
toggleAction.addEventListener('click', handleToggle);
stopAction.addEventListener('click', handleStop);
update();
html, body {
width: 100%;
height: 100%;
margin: 0;
padding: 0;
}
body {
display: flex;
justify-content: center;
align-items: center;
background: #000;
}
.timer {
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
gap: 0.5em;
}
.timer .timer-display {
font-family: monospace;
font-size: 3em;
background: #111;
color: #8F8;
border: thin solid #222;
padding: 0.25em;
}
.timer .timer-actions {
display: flex;
justify-content: center;
gap: 0.5em;
}
.timer .timer-actions button[data-action] {
font-family: monospace;
width: 6em;
border: thin solid #444;
background: #222;
color: #EEE;
padding: 0.5em;
cursor: pointer;
text-transform: uppercase;
}
.timer .timer-actions button[data-action]:hover {
background: #444;
border: thin solid #666;
color: #FFF;
}
<div class="timer">
<div class="timer-display"></div>
<div class="timer-actions">
<button data-action="toggle" data-state="initial">Start</button>
<button data-action="stop">Stop</button>
</div>
</div>

Note: This solution is not suitable if you like your interval works on the background, for example, playing audio or something else. But if you are confused for example about your animation not working properly when coming back to your page or tab, this is a good solution.
There are many ways to achieve this goal, maybe the "WebWorkers" is the most standard one but certainly, it's not the easiest and handy one, especially If you don't have enough Time, so you can try this way:
The basic concept:
build a name for your interval(or animation) and set your interval(animation), so it would run when user first time open your page : var interval_id = setInterval(your_func, 3000);
by $(window).focus(function() {}); and $(window).blur(function() {}); you can clearInterval(interval_id) everytime browser(tab) is deactived and ReRun your interval(animation) everytime browser(tab) would acive again by interval_id = setInterval();
Sample code:
var interval_id = setInterval(your_func, 3000);
$(window).focus(function() {
interval_id = setInterval(your_func, 3000);
});
$(window).blur(function() {
clearInterval(interval_id);
interval_id = 0;
});

Here's my rough solution
(function(){
var index = 1;
var intervals = {},
timeouts = {};
function postMessageHandler(e) {
window.postMessage('', "*");
var now = new Date().getTime();
sysFunc._each.call(timeouts, function(ind, obj) {
var targetTime = obj[1];
if (now >= targetTime) {
obj[0]();
delete timeouts[ind];
}
});
sysFunc._each.call(intervals, function(ind, obj) {
var startTime = obj[1];
var func = obj[0];
var ms = obj[2];
if (now >= startTime + ms) {
func();
obj[1] = new Date().getTime();
}
});
}
window.addEventListener("message", postMessageHandler, true);
window.postMessage('', "*");
function _setTimeout(func, ms) {
timeouts[index] = [func, new Date().getTime() + ms];
return index++;
}
function _setInterval(func, ms) {
intervals[index] = [func, new Date().getTime(), ms];
return index++;
}
function _clearInterval(ind) {
if (intervals[ind]) {
delete intervals[ind]
}
}
function _clearTimeout(ind) {
if (timeouts[ind]) {
delete timeouts[ind]
}
}
var intervalIndex = _setInterval(function() {
console.log('every 100ms');
}, 100);
_setTimeout(function() {
console.log('run after 200ms');
}, 200);
_setTimeout(function() {
console.log('closing the one that\'s 100ms');
_clearInterval(intervalIndex)
}, 2000);
window._setTimeout = _setTimeout;
window._setInterval = _setInterval;
window._clearTimeout = _clearTimeout;
window._clearInterval = _clearInterval;
})();

I was able to call my callback function at minimum of 250ms using audio tag and handling its ontimeupdate event. Its called 3-4 times in a second. Its better than one second lagging setTimeout

There is a workaround for this problem, although actually the tab must be made active in some window.
Make your inactive tab a separate browser window.
Don't make any other window maximized (unless the maximized window is behind yours).
This should give the browser the impression of always being active.
This is bit cumbersome, but also a quick win. Provided one has control over windows arrangement.

create a soundbar with Angularjs

I looked into different solutions, such as this one that I improved with a button : http://jsfiddle.net/3mhJJ/.
$(".button").click(function(){
$(".bar").each(function(i) {fluctuate($(this));});
});
I would like to be able to pause the recording, and also to stop the animation when the sound is over ( I didn't include it, but just imagine the sound lasts 10 seconds)
I have never worked with jQuery, but I am familiar with AngularJS, do you think there is any way for me to do this only with JQuery or by mixing JQuery and AngularJS together?
Otherwise, I'd like to recreate something like Soundcloud but I am not sure how hard it is.
Thanks for advices.

Not entirely sure that I understood what you're after but here's how to start/stop the animation:
http://jsfiddle.net/kyysdo4n/2/ (updated to include an auto-stop feature)
var stopAnimation = false;
var closeTimeoutHandle = null;
function fluctuate(bar) {
if(stopAnimation){
return;
}
var amplitude = Math.random() * 10;
console.log(amplitude);
var height = amplitude * 4;
//Animate the equalizer bar repeatedly
bar.animate({
height: height
}, function() {
fluctuate($(this));
});
}
$("#btnStart").click(function(i) {
stopAnimation = false;
fluctuate($('.bar'));
closeTimeoutHandle = setTimeout(function(){
stopAnimation = true;
}, 10 * 1000); //10 seconds
});
$("#btnStop").click(function(i) {
stopAnimation = true;
fluctuate($('.bar'));
// clear the timeout so that if the user starts the animation again
// it doesn't get stopped when the initial timeout gets called
if(closeTimeoutHandle){
clearTimeout(closeTimeoutHandle);
}
});
I'm not sure if this helps .. if it doesn't then please add more details, maybe more code ?

what speed up "setInterval" when you switch page?

Here is My page,It is a demo to test moving a element,but after you change your page sometime,and back to here,why the DIV move faster?
My css:
#box1 {
width: 900px;
height: 50px;
background-color: #000;
position: relative;
}
#box2 {
width: 50px;
height: 50px;
background-color: #a00;
position: absolute;
}
My HTML:
<div id="box1">
<div id="box2"></div>
</div>
My Js:
var box2 = document.getElementById("box2");
var remove = setInterval(function () {
box2.style.left = "0px";
var move = setInterval(function () {
var newLeft = Math.min(parseInt(box2.style.left) + 5, 850) + "px";
box2.style.left = newLeft;
if (newLeft == "850px") clearInterval(move)
}, 20);
}, 5000)

The rate of setInterval cannot be trusted. A browser might not fire it when the tab is not focused, and as well might fire it more often than needed.
The behaviour is standardisized in the current HTML5 draft on the WindowTimers interface (which does not mean it was implemented like that). There you will find the note:
This API does not guarantee that timers will run exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected.
and, even more explicit:
9) Optionally, wait a further user-agent defined length of time.
Note: This is intended to allow user agents to pad timeouts as needed to optimise the power usage of the device. For example, some processors have a low-power mode where the granularity of timers is reduced; on such platforms, user agents can slow timers down to fit this schedule instead of requiring the processor to use the more accurate mode with its associated higher power usage.
You might also want to have a look at the WindowAnimationTiming draft.
And if you do use setInterval/setTimeout in animations/clocks/etc, always measure the really elapsed time with Date objects (e.g. via Date.now()).

Some browsers don't bother to fire timeout/interval events if the window is unfocused. When the window regains focus, it fires all of them at once. It's a performance decision (Why fire an event every millisecond if the user won't even notice?), and, to my knowledge, there's no way to change this behavior.

Mozilla Firefox and Google Chrome both throttle the speed of ticks that an interval when the tab is inactive (Sources: http://pivotallabs.com/users/mrushakoff/blog/articles/2035-chrome-and-firefox-throttle-settimeout-setinterval-in-inactive-tabs, https://stackoverflow.com/a/6032591/1756941)
And so, as this answer suggests, capture the date and check it against the tick, to verify if it's working correctly, else compensate for the missing time..
JS:
var tick = 20;
var newLeft=0;
var box2 = document.getElementById("box2");
var remove = setInterval(function() {
box2.style.left = "0px";
var now, before = new Date();
var move = setInterval(function() {
now = new Date();
var elapsedTime = (now.getTime() - before.getTime());
if (elapsedTime > tick) {
console.log((Math.floor(elapsedTime / tick) * 5));
newLeft = Math.min(parseInt(box2.style.left) + (Math.floor(elapsedTime / tick) * 5), 850) + "px";
}
else {
newLeft = Math.min(parseInt(box2.style.left) + 5, 850) + "px";
}
box2.style.left = newLeft;
before = new Date();
if (newLeft == "850px"){clearInterval(move);}
}, tick);
}, 5000);
​
JSFiddle: http://jsfiddle.net/3jY8h/1/